Along with visual feedback, somatosensory feedback provides the nervous system with information regarding movement performance. Somatosensory system damage disrupts the normal feedback process, which can lead to a pins and needles sensation, or paresthaesia, and impaired movement control. The present study assessed the impact of temporarily induced median nerve paresthaesia, in individuals with otherwise intact sensorimotor function, on goal-directed reaching and grasping movements. Healthy, right-handed participants performed reach and grasp movements to five wooden Efron shapes, of which three were selected for analysis. Participants performed the task without online visual feedback and in two somatosensory conditions: 1) normal; and 2) disrupted somatosensory feedback. Disrupted somatosensory feedback was induced temporarily using a Digitimer (DS7AH) constant current stimulator. Participants' movements to shapes 15 or 30 cm to the right of the hand's start position were recorded using a 3 D motion analysis system at 300 Hz (Optotrak 3 D Investigator). Analyses revealed no significant differences for reaction time. Main effects for paresthaesia were observed for temporal and spatial aspects of the both the reach and grasp components of the movements. Although participants scaled their grip aperture to shape size under paresthaesia, the movements were smaller and more variable. Overall participants behaved as though they perceived they were performing larger and faster movements than they actually were. We suggest the presence of temporally induced paresthaesia affected online control by disrupting somatosensory feedback of the reach and grasp movements, ultimately leading to smaller forces and fewer corrective movements.

中文翻译：

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伸手和抓握都受到暂时诱发的感觉异常的影响。

除了视觉反馈，体感反馈还为神经系统提供有关运动表现的信息。体感系统损伤会扰乱正常的反馈过程，这会导致针刺感或感觉异常，以及运动控制受损。本研究评估了暂时诱导的正中神经感觉异常，在其他感觉运动功能完好的个体中，对目标导向的伸手和抓握动作的影响。健康、惯用右手的参与者对五种木制 Efron 形状进行伸手和抓握动作，其中三个被选中进行分析。参与者在没有在线视觉反馈和两种体感条件下执行任务：1）正常；2) 体感反馈中断。使用 Digitimer (DS7AH) 恒流刺激器暂时诱导中断的体感反馈。使用 300 Hz 的 3D 运动分析系统（Optotrak 3D Investigator）记录参与者向手起始位置右侧 15 或 30 厘米形状的运动。分析显示反应时间没有显着差异。在动作的伸手和抓握组件的时间和空间方面观察到感觉异常的主要影响。尽管参与者在感觉异常的情况下缩放了他们的抓地力大小以塑造尺寸，但动作更小且更可变。总体而言，参与者的行为好像他们认为他们正在执行比实际更大更快的运动。